Hierarchical Encapsulation and Rich sp<sup>2</sup> N Assist <scp>Sb<sub>2</sub>Se<sub>3</sub>‐Based Conversion‐Alloying</scp> Anode for <scp>Long‐Life</scp> Sodium‐ and Potassium‐Ion Storage
Shaokun Chong, Meng Ma, Lingling Yuan, Shuangyan Qiao, Shihong Dong, Huan Liu, Shi Xue Dou
Abstract
Sodium‐ and potassium‐ion batteries have exhibited great application potential in grid‐scale energy storage due to the abundant natural resources of Na and K. Conversion‐alloying anodes with high theoretical capacity and low‐operating voltage are ideal option for SIBs and PIBs but suffer the tremendous volume variations. Herein, a hierarchically structural design and sp 2 N‐doping assist a conversion‐alloying material, Sb 2 Se 3 , to achieve superior life span more than 1000 cycles. It is confirmed that the Sb 2 Se 3 evolves into nano grains that absorb on the sp 2 N sites and in situ form chemical bonding of C‐N‐Sb after initial discharge. Simulation results indicate that sp 2 N has more robust interaction with Sb and stronger adsorption capacities to Na + and K + than that of sp 3 N, which contributes to the durable cycling ability and high electrochemical activity, respectively. The ex situ transmission electron microscopy and X‐ray photoelectron spectroscopy results suggest that the Sb 2 Se 3 electrode experiences conversion‐alloying dual mechanisms based on 12‐electron transfer per formula unit.